Memory devices are typically provided as internal, semiconductor, integrated circuits in computers or other electronic devices. There are many different types of memory including random-access memory (RAM), read only memory (ROM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), and flash memory.
A flash memory is a type of memory that can be erased and reprogrammed in blocks instead of one byte at a time. A typical flash memory comprises a memory array that includes a large number of memory cells. Each of the memory cells includes a floating gate field-effect transistor capable of holding a charge. The cells are usually grouped into blocks of 64 pages of single level cells (SLC) or 128 pages of multilevel cells (MLC), where each page is typically 2048 bytes of data on 32 word lines. Each of the cells within a block can be electrically programmed on a random basis by charging the floating gate.
The data in a cell is determined by the presence or absence of charge on the floating gate. Each memory cell can be programmed as an SLC or MLC. Each cell's threshold voltage (Vt) determines the data that is stored in the cell. For example, in an SLC, a Vt of 0.5V can indicate a programmed cell while a Vt of −0.5V might indicate an erased cell. The multilevel cell has multiple Vt ranges that each indicates a different state. Multilevel cells can take advantage of the analog nature of a traditional flash cell by assigning a bit pattern to a specific voltage range for the cell. This technology permits the storage of two or more bits per cell, depending on the quantity of voltage ranges assigned to the cell. The charge can be removed from the floating gate by a block erase operation.
As the performance of systems incorporating flash memory increases, it is desirable for the programming and reading performance of the flash memory to increase as well. Increased memory performance would reduce the resulting data bottleneck that can occur when a faster system programs or reads a slower flash memory device.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a way to increase performance of a memory device.